Field of the Invention
The present invention relates to an improved process for capturing pollutants that are the result of the combustion in furnaces of pollutant releasing fuels such as coal, trash, and residual oil, particularly combustion carried out in boilers associated with steam produced for use in electricity generating stations or in industrial processing operations.
Description of the Related Art
Various processes have been disclosed for capturing undesirable pollutants resulting from the combustion of fuels. Some of those processes include the introduction into the furnace, at various locations within the furnace, of sorbents of various types, including alkaline-earth-metal-based compounds. Also previously known is a process in which the alkalinity of normal coarse fly ash is utilized and is partially effective in dealing with condensable acids, which enables a small reduction in flue gas exit temperature, with an accompanying gain in fuel thermal efficiency. However, that process permits capture of only a fraction of the pollutants and provides only about one fifth of the potential gain from a reduction of the flue gas exit temperature. In that regard, normal coarse fly ash includes only a minor fraction of the desirable micron-sized fly ash particles.